Ricky Ponting leaves the MCG after his dismissal in the second innings of the fourth Ashes Test. Photograph: Tom Shaw/Getty Images

For a cricketer there is seldom a perfect time to go. No matter the evidence of statistic or eye, there is always another big innings round the corner, another bowling performance there. Part of what sustains a top player is the belief in immortality. They go into a state of denial. But this series has stripped bare that notion. By the time Australia next play a Test series, in August, the order will have changed, both in their team and England's.

Time was, though, when the best players knew when it was right to hang up the boots. Cricket was a game for playing, not one on which to get rich. It was a self-indulgent activity that one day had to be traded in for the need to earn a living. The bigger wages were elsewhere. Those days are long gone. Cricketers are extremely well rewarded and few are going to earn as much money outside the game as they ever did playing.

Eight years ago the Ashes tour was run in conjunction with what effectively was a Steve Waugh valedictory series, culminating in his century at the Sydney Cricket Ground. Last time it was Shane Warne and Glenn McGrath saying their goodbyes to the faithful as they carved up England. But these farewells are rare. A glorious exit on your own terms may be one thing but there is no ignominy felt these days when the selectors tap a player on a shoulder and tell him the game is up. It is part of the deal now.

Australia will have some months to ponder on the dilemma caused by Ricky Ponting's slide. There is a decision to be made, not just about the captaincy but regarding his contribution as a player. Clearly he is near the end of the road, the years of batting at No3, the pivotal, most complex position in the order, taking their mental toll. Ponting could take the fractured finger and the long spell without Tests as a sign to make the break from the longer form of the game. But he believes that he can contribute to what he calls "the betterment of Australian cricket" by batting down the order and becoming a mentor. Perhaps his personal success or otherwise in the World Cup might dictate his future. But such is his earning power and his singular, almost obsessive devotion to the game that surely he will find it immensely difficult to sever the ties.

Should he continue, however, it will mean the end elsewhere, for the feeling is said to be that, as Australia look to rebuild their side towards regaining power, there will be room for only one of Ponting and Mike Hussey.

Sheer cussedness gave Hussey his place in the team for this series. Out of touch and all but out of the door before the first Test, Hussey, playing for Western Australia in the final Shield match before the Test side was chosen, followed an excruciatingly drawn-out nought with a caution-to-the-wind century that alone kept him in the team. For three subsequent Tests he held the batting together, only to falter at the MCG. But Hussey, too, would be reluctant to give up of his own accord. In the end that is what selectors are for.

Paul Collingwood may just be coming to the end of the line, too. The statistics are starting to tell an inescapable story of a Test career in decline. Since the middle of last summer, after he was rested for the Bangladesh series, he has scored only 189 runs in 11 innings, including a top score of 82 in the first of that sequence, and at an average of 17.2, against a career average of 40. In this series he totals 72 runs in five innings and there comes a point when that is no longer acceptable from a batsman in the top five whatever his credential, potential or value elsewhere.

There is slight mitigation. Between making four in the first innings in Brisbane and 42 in the first at Adelaide, he sat through 180 overs with all but his pads on while others filled their boots and was then required to come in and force the scoring. In Perth he was not alone in finding the pace, bounce and particularly the swing too much. It would be perfectly in keeping for him to make a hundred in Sydney, for he must play there. And if his batting currently looks even more of a struggle than it generally does, then his electric catching is an essential part of the fielding dynamic. The catch he took in Perth to dismiss Ponting should not be underestimated for the psychological damage it did.

Clearly, though, there is another decision to be made. Collingwood, 34, remains an essential part of England's World Cup plans and is the captain – a successful one, too – of the Twenty20 side. There is much cricket for him yet to play for England. But the end of this series might be a fine time for a line to be drawn under his Test career. Whether he comes to that decision himself or is encouraged to do so, the time has probably come. Things have to move on.